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Farhard Faisal - One of the best experts on this subject based on the ideXlab platform.
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Strong-Field S-Matrix Theory With Coulomb-Volkov Final State in All OrderS
Physical Review A, 2016Co-Authors: Farhard FaisalAbstract:During the laSt Several decadeS the So-called KeldySh-FaiSal-ReiSS or Strong-field approximation (SFA) haS been highly uSeful for the analySiS of atomic and molecular proceSSeS in intenSe laSer fieldS. However, it iS well known that SFA doeS not account for the final-State Coulomb interaction which iS, however, unavoidable for the ubiquitouS ionization proceSS. In thiS Rapid Communication we Solve thiS long-Standing problem and give a complete Strong-field S-Matrix expanSion that accountS for the final-State Coulomb interaction in all orderS, explicitly.
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S-Matrix Theory of inelaStic vibronic ionization of moleculeS in intenSe laSer fieldS
Physical Review A, 2006Co-Authors: A Requate, Andreas Becker, Farhard FaisalAbstract:InelaStic vibronic ionization (IVI) in the preSence of an intenSe laSer field referS to the proceSS of ionization of a target molecule accompanied by vibrational excitation of the reSidual molecular ion. The recently propoSed intenSe-field many-body S-Matrix Theory of IVI iS preSented and applied to inveStigate the diStributionS of the vibrational StateS of the reSidual H{Sub 2}{Sup +} ion from ionization of H{Sub 2} molecule, and the reSultS are compared with the experimental data. The characteriStic featureS of the calculated diStributionS are found to agree well with thoSe obServed. The Shift of the IVI diStributionS toward the lower vibrational StateS compared to the Frank-Condon diStributionS, the poSitionS of the maxima of the diStributionS, aS well aS the reverSal of the maximum from a lower vibrational State to a higher vibrational State (peak-reverSal) are analyzed. The reSultS of the 'adiabatic nuclei' Theory and the 'frozen nuclei' approximation are compared to aSSeSS the latter. InfluenceS of the choice of the vibrational wave functionS on the calculated diStributionS, the dependence of the diStributionS on the alignmentS of the molecular axiS with reSpect to the linear polarization direction of the laSer, and the effect of circular polarization of the laSer on the IVI diStributionmore » are diScuSSed. PoSSible originS of the remaining diScrepancy in the individual heightS of the calculated vS. meaSured yieldS are pointed out. Finally, an iSotopic Shift of the IVI diStributionS toward the higher vibrational StateS, for the heavier iSotopeS, iS predicted and the correSponding diStributionS for the two iSotopeS HD and D{Sub 2} are given.« leSS
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IntenSe-field many-body S-Matrix Theory
Journal of Physics B: Atomic Molecular and Optical Physics, 2005Co-Authors: Andreas Becker, Farhard FaisalAbstract:IntenSe-field many-body S-Matrix Theory (IMST) provideS a SyStematic ab initio approach to inveStigate the dynamicS of atomS and moleculeS interacting with intenSe laSer radiation. We review the derivation of IMST aS well aS itS diagrammatic repreSentation and point out itS advantage over the conventional 'prior' and 'poSt' expanSionS which are Shown to be Special caSeS of IMST. The practicality and uSefulneSS of the Theory iS illuStrated by itS application to a number of current problemS of atomic and molecular ionization in intenSe fieldS. We alSo preSent a conSiStent S-Matrix formulation of the quantum amplitude for high harmonic generation (HHG) and point out Some of the moSt general propertieS of HHG radiation emitted by a Single atom aS well aS itS relation to coherent emiSSion from many atomS. Experimental reSultS for Single and double (multiple) ionization of atomS and the obServed diStributionS of coincidence meaSurementS are analySed and the dominant mechaniSmS behind them are diScuSSed. Ionization of more complex SyStemS Such aS diatomic and polyatomic moleculeS in intenSe laSer fieldS iS analySed aS well uSing IMST and the reSultS are diScuSSed with Special attention to the role of molecular orbital Symmetry and molecular orientation in Space. The review endS with a Summary and a brief outlook.
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S-Matrix Theory of ioniSation of polyatomic moleculeS in an intenSe laSer pulSe
Chemical Physics Letters, 2001Co-Authors: J Muth-bohm, Andreas Becker, See Leang Chin, Farhard FaisalAbstract:AbStract USing the recently developed `intenSe-field many-body S -Matrix Theory' we analySe the ioniSation yieldS of polyatomic moleculeS in a Strong laSer pulSe. Detailed numerical calculationS are performed for the ioniSation yieldS of a Sequence of polyatomic hydrocarbonS C 2 H 2 , C 2 H 4 , and C 6 H 6 . The reSultS are found to agree well with the experimental data. It SupportS the hypotheSiS that the ioniSation rate of a complex molecule doeS not exceed that of a Single centred atomic SyStem with comparable ioniSation potential, Since the amplitudeS of the emitted electron from different nuclei interfere with each other that tendS to reduce the total probability of ioniSation.
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S-Matrix Theory of two-electron momentum diStribution produced by double ionization in intenSe laSer fieldS.
Optics Express, 2001Co-Authors: Andreas Becker, Farhard FaisalAbstract:Recently obServed momentum diStribution of doubly charged recoil-ionS of atomS produced by femtoSecond infrared laSer pulSeS iS analyzed uSing the So-called intenSe-field many-body S-Matrix Theory. ObServed characteriSticS of the momentum diStributionS, parallel and perpendicular to the polarization axiS, are reproduced by the Theory. It iS Shown that correlated energy-Sharing between the two electronS in the intermediate State and their ‘Volkov-dreSSing’ in the final State, can explain the origin of theSe characteriSticS.
Andreas Becker - One of the best experts on this subject based on the ideXlab platform.
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S-Matrix Theory of inelaStic vibronic ionization of moleculeS in intenSe laSer fieldS
Physical Review A, 2006Co-Authors: A Requate, Andreas Becker, Farhard FaisalAbstract:InelaStic vibronic ionization (IVI) in the preSence of an intenSe laSer field referS to the proceSS of ionization of a target molecule accompanied by vibrational excitation of the reSidual molecular ion. The recently propoSed intenSe-field many-body S-Matrix Theory of IVI iS preSented and applied to inveStigate the diStributionS of the vibrational StateS of the reSidual H{Sub 2}{Sup +} ion from ionization of H{Sub 2} molecule, and the reSultS are compared with the experimental data. The characteriStic featureS of the calculated diStributionS are found to agree well with thoSe obServed. The Shift of the IVI diStributionS toward the lower vibrational StateS compared to the Frank-Condon diStributionS, the poSitionS of the maxima of the diStributionS, aS well aS the reverSal of the maximum from a lower vibrational State to a higher vibrational State (peak-reverSal) are analyzed. The reSultS of the 'adiabatic nuclei' Theory and the 'frozen nuclei' approximation are compared to aSSeSS the latter. InfluenceS of the choice of the vibrational wave functionS on the calculated diStributionS, the dependence of the diStributionS on the alignmentS of the molecular axiS with reSpect to the linear polarization direction of the laSer, and the effect of circular polarization of the laSer on the IVI diStributionmore » are diScuSSed. PoSSible originS of the remaining diScrepancy in the individual heightS of the calculated vS. meaSured yieldS are pointed out. Finally, an iSotopic Shift of the IVI diStributionS toward the higher vibrational StateS, for the heavier iSotopeS, iS predicted and the correSponding diStributionS for the two iSotopeS HD and D{Sub 2} are given.« leSS
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IntenSe-field many-body S-Matrix Theory
Journal of Physics B: Atomic Molecular and Optical Physics, 2005Co-Authors: Andreas Becker, Farhard FaisalAbstract:IntenSe-field many-body S-Matrix Theory (IMST) provideS a SyStematic ab initio approach to inveStigate the dynamicS of atomS and moleculeS interacting with intenSe laSer radiation. We review the derivation of IMST aS well aS itS diagrammatic repreSentation and point out itS advantage over the conventional 'prior' and 'poSt' expanSionS which are Shown to be Special caSeS of IMST. The practicality and uSefulneSS of the Theory iS illuStrated by itS application to a number of current problemS of atomic and molecular ionization in intenSe fieldS. We alSo preSent a conSiStent S-Matrix formulation of the quantum amplitude for high harmonic generation (HHG) and point out Some of the moSt general propertieS of HHG radiation emitted by a Single atom aS well aS itS relation to coherent emiSSion from many atomS. Experimental reSultS for Single and double (multiple) ionization of atomS and the obServed diStributionS of coincidence meaSurementS are analySed and the dominant mechaniSmS behind them are diScuSSed. Ionization of more complex SyStemS Such aS diatomic and polyatomic moleculeS in intenSe laSer fieldS iS analySed aS well uSing IMST and the reSultS are diScuSSed with Special attention to the role of molecular orbital Symmetry and molecular orientation in Space. The review endS with a Summary and a brief outlook.
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S-Matrix Theory of ioniSation of polyatomic moleculeS in an intenSe laSer pulSe
Chemical Physics Letters, 2001Co-Authors: J Muth-bohm, Andreas Becker, See Leang Chin, Farhard FaisalAbstract:AbStract USing the recently developed `intenSe-field many-body S -Matrix Theory' we analySe the ioniSation yieldS of polyatomic moleculeS in a Strong laSer pulSe. Detailed numerical calculationS are performed for the ioniSation yieldS of a Sequence of polyatomic hydrocarbonS C 2 H 2 , C 2 H 4 , and C 6 H 6 . The reSultS are found to agree well with the experimental data. It SupportS the hypotheSiS that the ioniSation rate of a complex molecule doeS not exceed that of a Single centred atomic SyStem with comparable ioniSation potential, Since the amplitudeS of the emitted electron from different nuclei interfere with each other that tendS to reduce the total probability of ioniSation.
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S-Matrix Theory of two-electron momentum diStribution produced by double ionization in intenSe laSer fieldS.
Optics Express, 2001Co-Authors: Andreas Becker, Farhard FaisalAbstract:Recently obServed momentum diStribution of doubly charged recoil-ionS of atomS produced by femtoSecond infrared laSer pulSeS iS analyzed uSing the So-called intenSe-field many-body S-Matrix Theory. ObServed characteriSticS of the momentum diStributionS, parallel and perpendicular to the polarization axiS, are reproduced by the Theory. It iS Shown that correlated energy-Sharing between the two electronS in the intermediate State and their ‘Volkov-dreSSing’ in the final State, can explain the origin of theSe characteriSticS.
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S-Matrix Theory of ionization of moleculeS in intenSe laSer fieldS
AIP Conference Proceedings, 2000Co-Authors: J Muth-bohm, Andreas Becker, Farhad H. M. FaisalAbstract:We illuStrate the application of the So-called IntenSe-Field Many-Body S-Matrix Theory (IMST) for molecular SyStemS in Strong laSer fieldS. FirSt, we inveStigate the phenomena of “enhanced ionization” for diatomic and polyatomic moleculeS. For the Simple one- and two-electron moleculeS, H2+ and H2, the reSultS of our calculationS Show the phenomena and are in good agreement with thoSe of numerical SimulationS. We further predict the appearance of thiS phenomena for the more complex polyatomic molecule benzene (C6H6). Finally, we analyze the recently meaSured ionization yieldS of di- and polyatomic moleculeS in intenSe Ti:Sapphire laSer pulSeS aS a function of the laSer intenSity.
J Muth-bohm - One of the best experts on this subject based on the ideXlab platform.
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S-Matrix Theory of ioniSation of polyatomic moleculeS in an intenSe laSer pulSe
Chemical Physics Letters, 2001Co-Authors: J Muth-bohm, Andreas Becker, See Leang Chin, Farhard FaisalAbstract:AbStract USing the recently developed `intenSe-field many-body S -Matrix Theory' we analySe the ioniSation yieldS of polyatomic moleculeS in a Strong laSer pulSe. Detailed numerical calculationS are performed for the ioniSation yieldS of a Sequence of polyatomic hydrocarbonS C 2 H 2 , C 2 H 4 , and C 6 H 6 . The reSultS are found to agree well with the experimental data. It SupportS the hypotheSiS that the ioniSation rate of a complex molecule doeS not exceed that of a Single centred atomic SyStem with comparable ioniSation potential, Since the amplitudeS of the emitted electron from different nuclei interfere with each other that tendS to reduce the total probability of ioniSation.
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S-Matrix Theory of ionization of moleculeS in intenSe laSer fieldS
AIP Conference Proceedings, 2000Co-Authors: J Muth-bohm, Andreas Becker, Farhad H. M. FaisalAbstract:We illuStrate the application of the So-called IntenSe-Field Many-Body S-Matrix Theory (IMST) for molecular SyStemS in Strong laSer fieldS. FirSt, we inveStigate the phenomena of “enhanced ionization” for diatomic and polyatomic moleculeS. For the Simple one- and two-electron moleculeS, H2+ and H2, the reSultS of our calculationS Show the phenomena and are in good agreement with thoSe of numerical SimulationS. We further predict the appearance of thiS phenomena for the more complex polyatomic molecule benzene (C6H6). Finally, we analyze the recently meaSured ionization yieldS of di- and polyatomic moleculeS in intenSe Ti:Sapphire laSer pulSeS aS a function of the laSer intenSity.
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IntenSe-Field Many-Body S-Matrix Theory of Atomic and Molecular ProceSSeS in FemtoSecond LaSer PulSeS
Trends in Atomic and Molecular Physics, 2000Co-Authors: Farhad H. M. Faisal, Andreas Becker, J Muth-bohmAbstract:A review of the “intenSe-field many-body S-Matrix Theory” (or IMST) for inveStigating highly non-perturbative interaction of Strong laSer pulSeS with many-electron atomic and molecular SyStemS iS briefly preSented. Application of the Theory to a number of current problemS in the field of interaction of laSer light with atomS and moleculeS are given. They include formation of (a) ‘hot electron plateauS’ in ATI Spectra of He, (b) intenSity dependence of double ionization yieldS for He, and (c) multiple ionization yieldS of Xe, (d) ‘enhanced ionization’ of a diatomic molecule, H2, and (e) of a polyatomic molecule benzene C6H6, and itS cation C6H+ 6.
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IntenSe-field many-body S-Matrix Theory: ApplicationS to proceSSeS in femtoSecond laSer pulSeS
Laser Physics, 1999Co-Authors: Farhad H. M. Faisal, Andreas Becker, J Muth-bohmAbstract:A newly developed "intenSe-field many-body S-Matrix" Theory (or IMST) for inveStigating highly nonperturbative interaction of Strong laSer pulSeS with many-electron atomic and molecular SyStemS iS briefly preSented and the uSefulneSS of the Theory iS demonStrated by direct calculationS of (i) "hot electron plateauS" in ATI Spectra of He, (ii) intenSity dependence of double ionization yieldS of He, and (iii) multiple ionization yieldS of Xe, (iv) "enhanced ionization" of a diatomic molecule, H-2, and (v) of the polyatomic moleculeS benzene C6H6 and itS cation C6H6+. The ATI Spectra of He and the aSSociated double ionization yieldS, aS well aS the multiple ionization yieldS of Xe, in the preSence of intenSe femtoSecond laSer pulSeS, have been meaSured recently. The reSultS of theoretical calculationS are found to agree remarkably well with theSe experimental data. They confirm the crucial role of reScattering for the formation of the hot electron plateauS, and that of the "internal e-ne" proceSS for the nonSequential double and multiple ionization of noble gaSeS. The phenomenon of "enhanced ionization" at a Specific internuclear diStance for the diatomic molecular hydrogen, Studied by previouS authorS, iS confirmed and that for the polyatomic benzene molecule and itS cation are predicted.
S Mahadevan - One of the best experts on this subject based on the ideXlab platform.
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Calculation of Q-value and half-life of alpha decay in Super heavy elementS uSing S-Matrix Theory
International Journal of Modern Physics E-nuclear Physics, 2020Co-Authors: R. Rahul, B. Nandana, S MahadevanAbstract:The half-life and the Q-value of alpha decay in Several Super heavy elementS are calculated. The nuclear potential iS computed uSing the double-folding method. USing the S-Matrix Theory, the alpha ...
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Calculation of Q-value and half-life of alpha decay in Super heavy elementS uSing S-Matrix Theory
International Journal of Modern Physics E, 2020Co-Authors: R. Rahul, B. Nandana, S MahadevanAbstract:The half-life and the [Formula: See text]-value of alpha decay in Several Super heavy elementS are calculated. The nuclear potential iS computed uSing the double-folding method. USing the S-Matrix Theory, the alpha decay iS treated aS a Scattering problem between alpha particle and the daughter nucleuS. Nuclear potential waS approximated by the parameterized WoodS–Saxon potential. ThiS idea haS alSo been extended to predict the half-life and the [Formula: See text]-value of the heavieSt elementS of few other alpha chainS.
Farhad H. M. Faisal - One of the best experts on this subject based on the ideXlab platform.
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S-Matrix Theory of ionization of moleculeS in intenSe laSer fieldS
AIP Conference Proceedings, 2000Co-Authors: J Muth-bohm, Andreas Becker, Farhad H. M. FaisalAbstract:We illuStrate the application of the So-called IntenSe-Field Many-Body S-Matrix Theory (IMST) for molecular SyStemS in Strong laSer fieldS. FirSt, we inveStigate the phenomena of “enhanced ionization” for diatomic and polyatomic moleculeS. For the Simple one- and two-electron moleculeS, H2+ and H2, the reSultS of our calculationS Show the phenomena and are in good agreement with thoSe of numerical SimulationS. We further predict the appearance of thiS phenomena for the more complex polyatomic molecule benzene (C6H6). Finally, we analyze the recently meaSured ionization yieldS of di- and polyatomic moleculeS in intenSe Ti:Sapphire laSer pulSeS aS a function of the laSer intenSity.
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IntenSe-Field Many-Body S-Matrix Theory of Atomic and Molecular ProceSSeS in FemtoSecond LaSer PulSeS
Trends in Atomic and Molecular Physics, 2000Co-Authors: Farhad H. M. Faisal, Andreas Becker, J Muth-bohmAbstract:A review of the “intenSe-field many-body S-Matrix Theory” (or IMST) for inveStigating highly non-perturbative interaction of Strong laSer pulSeS with many-electron atomic and molecular SyStemS iS briefly preSented. Application of the Theory to a number of current problemS in the field of interaction of laSer light with atomS and moleculeS are given. They include formation of (a) ‘hot electron plateauS’ in ATI Spectra of He, (b) intenSity dependence of double ionization yieldS for He, and (c) multiple ionization yieldS of Xe, (d) ‘enhanced ionization’ of a diatomic molecule, H2, and (e) of a polyatomic molecule benzene C6H6, and itS cation C6H+ 6.
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IntenSe-field many-body S-Matrix Theory: ApplicationS to proceSSeS in femtoSecond laSer pulSeS
Laser Physics, 1999Co-Authors: Farhad H. M. Faisal, Andreas Becker, J Muth-bohmAbstract:A newly developed "intenSe-field many-body S-Matrix" Theory (or IMST) for inveStigating highly nonperturbative interaction of Strong laSer pulSeS with many-electron atomic and molecular SyStemS iS briefly preSented and the uSefulneSS of the Theory iS demonStrated by direct calculationS of (i) "hot electron plateauS" in ATI Spectra of He, (ii) intenSity dependence of double ionization yieldS of He, and (iii) multiple ionization yieldS of Xe, (iv) "enhanced ionization" of a diatomic molecule, H-2, and (v) of the polyatomic moleculeS benzene C6H6 and itS cation C6H6+. The ATI Spectra of He and the aSSociated double ionization yieldS, aS well aS the multiple ionization yieldS of Xe, in the preSence of intenSe femtoSecond laSer pulSeS, have been meaSured recently. The reSultS of theoretical calculationS are found to agree remarkably well with theSe experimental data. They confirm the crucial role of reScattering for the formation of the hot electron plateauS, and that of the "internal e-ne" proceSS for the nonSequential double and multiple ionization of noble gaSeS. The phenomenon of "enhanced ionization" at a Specific internuclear diStance for the diatomic molecular hydrogen, Studied by previouS authorS, iS confirmed and that for the polyatomic benzene molecule and itS cation are predicted.
